There is no equivalence.
A quart is a measure of volume. 9x9 is a non-specific measure of area. The two measure different things and, according to basic principles of dimensional analysis, conversion from one to the other is not valid without some addition information.
The casserole measure is non-specific because the question does not specify whether it is 9 in x 9 in, or 9 cm x 9 cm (unlikely) or 9 dm x 9 dm.
3 quarts - If you look in the bottom of the pan it is normally etched in stating how many quarts and Liters it will hold
the 9X13 holds 3 quarts
Pour 2 quarts of water into the 9 x 13 pan and you will see for yourself - that's what I always do if I'm not sure.
Well, honey, it really depends on how hungry your guests are! A standard 9 x 13 inch casserole pan can typically serve around 8-12 people, but let's be real - if you're serving a bunch of hungry football players, you might want to double that recipe! Just remember, it's always better to have leftovers than to run out of food.
about 5 and 1/2 quarts will fit in that pan
9 quarts + 9 pints = 13 quarts 1 pint
17 quarts
9 fluid ounces is about 0.28 quarts.
9 pints is 4.5 quarts.
1 gallon = 4 quarts 9 quarts = 2.25 gallons
approximately 2 quarts.
There are 4 quarts in a gallon. Therefore, 9 gallons is equal to 9 x 4 = 36 quarts.